From: Bruce Richardson <bruce.richardson@intel.com>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] pmdinfogen: fix resource leak of FILE object
Date: Fri, 2 Feb 2018 15:51:12 +0000 [thread overview]
Message-ID: <20180202155112.GB20444@bricha3-MOBL3.ger.corp.intel.com> (raw)
In-Reply-To: <20180202154743.GA20444@bricha3-MOBL3.ger.corp.intel.com>
On Fri, Feb 02, 2018 at 03:47:43PM +0000, Bruce Richardson wrote:
> On Fri, Feb 02, 2018 at 07:44:39AM -0500, Neil Horman wrote:
> > On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> > > Coverity flags an issue where the resources used by the FILE object for
> > > the temporary input file are leaked. This is a very minor issue, but is
> > > easily fixed, while also avoiding later problems where we try to close
> > > an invalid file descriptor in the failure case.
> > >
> > > The fix is to use "dup()" to get a new file descriptor number rather than
> > > using the value directly from fileno. This allows us to close the file
> > > opened with tmpfile() within in scope block, while allowing the duplicate
> > > to pass to the outer block and be closed when the function terminates.
> > >
> > > As a side-effect I/O in the function is therefore changed from using stdio
> > > fread/fwrite to read/write system calls.
> > >
> > > Coverity issue: 260399
> > > Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> > >
> > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > ---
> > > buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
> > > 1 file changed, 10 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
> > > index 45b267346..0f35ca46b 100644
> > > --- a/buildtools/pmdinfogen/pmdinfogen.c
> > > +++ b/buildtools/pmdinfogen/pmdinfogen.c
> > > @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned long *size)
> > > /* from stdin, use a temporary file to mmap */
> > > FILE *infile;
> > > char buffer[1024];
> > > - size_t n;
> > > + int n;
> > >
> > > infile = tmpfile();
> > > if (infile == NULL) {
> > > perror("tmpfile");
> > > return NULL;
> > > }
> > > - while (!feof(stdin)) {
> > > - n = fread(buffer, 1, sizeof(buffer), stdin);
> > > - if (fwrite(buffer, 1, n, infile) != n)
> > > + fd = dup(fileno(infile));
> > > + fclose(infile);
> > > + if (fd < 0)
> > > + return NULL;
> > > +
> > > + n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > > + while (n > 0) {
> > > + if (write(fd, buffer, n) != n)
> > > goto failed;
> > > + n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > > }
> > > - fflush(infile);
> > > - fd = fileno(infile);
> > > }
> > >
> > > if (fstat(fd, &st))
> > > --
> > > 2.14.3
> > >
> > >
> >
> > Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
> > calling close?
> >
> > like
> > failed:
> > if (fd >= 0)
> > close(fd);
> >
> That would fix the problem of calling goto failed with fd set to -1, but
> would not fix the resource issue that coverity was complaining about. We
> were allocating a stdio FILE object, then taking just the fileno of it
> and letting the file number go out of scope. This cleans this that up,
s/file number/FILE object ptr/
> so that we just use file numbers and properly close the FILE * once it's
> outlived its usefulness.
>
> BTW: I did investigate using open and O_TMPFILE in place of tmpfile()
> call, but while it would work great on Linux, it's not available
> elsewhere, so tmpfile looks the best option.
>
> Regards,
> /Bruce
next prev parent reply other threads:[~2018-02-02 15:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-02 12:00 Bruce Richardson
2018-02-02 12:44 ` Neil Horman
2018-02-02 15:47 ` Bruce Richardson
2018-02-02 15:51 ` Bruce Richardson [this message]
2018-02-02 18:47 ` Neil Horman
2018-02-06 0:16 ` Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180202155112.GB20444@bricha3-MOBL3.ger.corp.intel.com \
--to=bruce.richardson@intel.com \
--cc=dev@dpdk.org \
--cc=nhorman@tuxdriver.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).